When applying coatings that contain a high amount of solids such as industrial coatings, maintenance coatings or paints, there is a tendency for the coating to sag or run. This tendency is especially prevalent when a workpiece, which is to accept the coating, is in a vertical position. Regarding workpieces that are vertically oriented, the coating may droop or sag due to gravity so that the thickness of the film formed when the coating is ultimately dried is uneven. Some sagging may occur by influence of gravity when the coating is applied. However, such sagging is more particularly a problem when baking the applied coating. An approach to overcome the sag problem is to include a rheology control agent in the coating so that the resultant effect of gravity is lessened. Such rheology control agents basically cause the coating to be shear thinning and to have high viscosity (decreased fluidity) at low shear while providing sufficiently low viscosity at high shear to permit flow and leveling on the workpiece.
U.S. Pat. No. 4,451,597 (Victorius, May 29, 1984) relates to coating composition useful as the exterior finish on automobiles and trucks and contains about 25-50% by weight of a binder of film-forming constituents and 50-75% by weight of a volatile organic solvent carrier and additionally contains 2-150% by weight, based on the weight of the binder, of pigment; the binder is about 20-70% by weight of an acrylic polymer containing reactive hydroxyl, carboxyl, amide groups or any mixture of such groups, about 0-40% by weight of a hydroxy-terminated polyester urethane resin and about 25-40% by weight of an alkylated melamine formaldehyde crosslinking resin; in addition the composition contains about 4-20% by weight, based on the weight of the binder, of a rheology control agent of an alcohol soluble cellulose acetate butyrate having a buryryl (sic) content of about 40-50% by weight, a hydroxyl content of about 4-5% by weight and a viscosity of about 0.2-0.4 second.
U.S. Pat. No. 5,034,444 (Yun et al., Jul. 23, 1991) discloses a rheology additive for non-aqueous coating compositions. The additive may be the reaction product of an alkoxylated aliphatic nitrogen-containing compound, an aliphatic diamine or mixtures thereof, and an organic polycarboxylic anhydride or acid, an alkanediol polyepoxide ether, or mixtures thereof. The additive provides excellent anti-sag and storage stability properties, particularly for high solids coating compositions, without causing a significant increase in viscosity. Also disclosed are coating compositions containing the additive.
U.S. Pat. No. 5,086,104 (Wada et al., Feb. 4, 1992) discloses polyester resin compositions which include a crystalline thermoplastic polyester resin (such as polybutylene terephthalate), a polyester elastomer (such as a copolymer including recurring hard and soft segments) and between 0.005 to 10 parts by weight, based on 100 parts of the crystalline and elastomeric resins, of an amide compound having the formula ##STR1## wherein R is an organic group such as an aromatic ring, X is an alkylene of C.sub.2 to C.sub.10 such as ethylene and propylene, Y is --COOH, --OH, --SH or --NH.sub.2 and n is 2 to 4, inclusive.
U.S. Pat. No. 4,321,098 (Lal, Jun. 14, 1994) relates to a composition mixture comprising (i) at least one ester-acid, ester-salt or mixtures thereof and (ii) at least one amidic-acid, amidic-salt or mixtures thereof and polymer fabrics treated with the same. The treated polymer fabrics have improved wicking-wetting characteristics. The treated polymer fabrics maintain these characteristics upon repeated exposure to aqueous fluids.
U.S. Pat. No. 5,369,184 (Burgoyne, Jr. et al., Nov. 29, 1994) relates to resins which comprise polymers which contain multiple acetal groups that have been developed which are useful for crosslinking and adhesion promotion in coating and adhesive applications. The polymers which make up these resins are prepared by the addition of aminoacetals to polymers containing anhydride functionality. The polymers are modified by titration with ammonia or a primary or secondary amine which solubilizes the polymer in aqueous systems.
U.S. Pat. No. 5,374,682 (Gouda et al., Dec. 20, 1994) is directed to a thermosetting coating composition that contains (a) an acrylic resin having hydroxyl groups and epoxy groups in a molecule thereof; (b) a resin prepared from a monomer having an unsaturated group and an acid anhydride group the acid anhydride group being half-esterified, half-thioesterified and/or half-amidized; (c) at least one of hydroxyl group-containing resin selected from the group consisting of an acrylic resin containing hydroxyl groups and carboxyl groups, a fluorine-containing copolymer resin and a polyester resin; and (d) a melamine resin.
U.S. Pat. No. 5,412,023 (Hille et al., May 2, 1995) relates to aqueous dispersions of crosslinked polymer microparticles, prepared in an aqueous medium from a polymer, optionally dissolved in an organic solvent, said polymer bearing at least two hydroxyl groups and comprising a number of ionic groups sufficient for the formation of a stable aqueous dispersion, as the component (A) and one further component (B) at an elevated temperature, characterized in that component (A) is a polyesterpolyol, a polyurethane or a polyacrylate having an acid value of from 5 to 168, and that component (B) is an aminoplast resin consisting of molecules containing at least two reactive groups consisting of hydroxyl and/or amino and/or ether groups, that the ratio by weight of component (A) to component (B) is between 30:70 and 95:5, and that the dispersion is stable and usable in water and/or an organic solvent or mixtures thereof. The reference further relates to a process for producing these dispersions, the use thereof and coating compositions containing aid dispersions.
U.S. Pat. No. 5,536,871 (Santhanam, Jul. 16, 1996) is directed to a liquid, pourable rheology additive especially usefull for thickening liquid organic compositions which comprises the reaction product of a defined polyalkoxylated nitrogen-containing compound, polycarboxylic acid and a liquid diamine. The additive, which exists in a pourable, pumpable form at up to a 100% rheologically active composition, exhibits excellent thickening efficiency for systems including inks, epoxies, polyesters, paints, greases and other systems, including ease of dispersibility, without adversely affecting gloss. The additive operates by both an associative and a reaction mechanism to provide rheology viscosity properties to such systems, and is also similarly useful for aqueous systems.